custom-space.h

Go to the documentation of this file.

// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef INCLUDE_CPPGC_CUSTOM_SPACE_H_
#define INCLUDE_CPPGC_CUSTOM_SPACE_H_
 
#include <stddef.h>
 
namespace cppgc {
 
struct CustomSpaceIndex {
  constexpr CustomSpaceIndex(size_t value) : value(value) {}  // NOLINT
  size_t value;
};
 
class CustomSpaceBase {
 public:
  virtual ~CustomSpaceBase() = default;
  virtual CustomSpaceIndex GetCustomSpaceIndex() const = 0;
  virtual bool IsCompactable() const = 0;
};
 
template <typename ConcreteCustomSpace>
class CustomSpace : public CustomSpaceBase {
 public:
  static constexpr bool kSupportsCompaction = false;
 
  CustomSpaceIndex GetCustomSpaceIndex() const final {
    return ConcreteCustomSpace::kSpaceIndex;
  }
  bool IsCompactable() const final {
    return ConcreteCustomSpace::kSupportsCompaction;
  }
};
 
template <typename T, typename = void>
struct SpaceTrait {
  using Space = void;
};
 
namespace internal {
 
template <typename CustomSpace>
struct IsAllocatedOnCompactableSpaceImpl {
  static constexpr bool value = CustomSpace::kSupportsCompaction;
};
 
template <>
struct IsAllocatedOnCompactableSpaceImpl<void> {
  // Non-custom spaces are by default not compactable.
  static constexpr bool value = false;
};
 
template <typename T>
struct IsAllocatedOnCompactableSpace {
 public:
  static constexpr bool value =
      IsAllocatedOnCompactableSpaceImpl<typename SpaceTrait<T>::Space>::value;
};
 
}  // namespace internal
 
}  // namespace cppgc
 
#endif  // INCLUDE_CPPGC_CUSTOM_SPACE_H_